Biomedical Engineering Reference
In-Depth Information
Table 9.1
Many cell types are capable of producing a whole range of interleukins.
T-lymphocytes are capable of producing all the interleukins, with the possible
exception of IL-7 and IL-15. Many cell types producing multiple interleukins can
also produce additional cytokines. For example, both macrophages and fi broblasts
are capable of producing several interleukins, CSFs and PDGF
Cell type
Interleukins produced
Macrophages
Eosinophils
Vascular endothelial cells
Fibroblasts
Keratinocytes
IL-1, IL-6, IL-10, IL-12
IL-3, IL-5
IL-1, IL-6, IL-8
IL-1, IL-6, IL-8, IL-11
IL-1, IL-6, IL-8, IL-10
receptor binding triggers alternative signal transduction events, including promoting an increase
in intracellular calcium concentration, or inducing hydrolysis of phosphatidylethanolamine with
release of diacyl glycerol.
The sum total of biological responses induced by the interleukins is large, varied and exceedingly
complex. These cytokines regulate a variety of physiological and pathological conditions,
including:
•
normal and malignant cell growth;
•
all aspects of the immune response;
•
regulation of infl ammation.
Several interleukins, particularly those capable of modulating transformed cell growth, as well
as those exhibiting immunostimulatory properties, enjoy signifi cant clinical interest. As with other
cytokines, the advent of recombinant DNA technology facilitates production of these molecules in
quantities suffi cient to meet actual/potential medical needs. Thus far, only two interleukin-based
products have gained approval for general medical use ('Proleukin', an IL-2 and 'Neumega', an
IL-11; see later) and these interleukins, along with IL-1, form the focus of much of this chapter.
Literature detailing additional interleukins is cited in the 'Further reading' section, to which the
interested reader is referred.
9.2 Interleukin-2
IL-2, also known as T-cell growth factor, represents the most studied member of the interleukin
family. It was the fi rst T-cell growth factor to be identifi ed and it plays a central role in the immune
response. It is produced exclusively by T-lymphocytes (especially T-helper cells), in response to
activation by antigen and mitogens.
Human IL-2 is a single-chain polypeptide containing 133 amino acids. It is a glycopro-
tein, the carbohydrate component being attached via an O-linked glycosidic bond to threonine
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